Adjuvants alter the physical–chemical properties of pesticide formulations, influencing either the droplet size or drift phenomenon. Selecting the appropriate adjuvant and understanding its characteristics can contribute to the efficiency of Plant Protection Product (PPP) application. This reduces drift losses and promotes better deposition on the crop. The objective of this study was to evaluate the effects of four commercial adjuvants based on mineral oil (Agefix and Assist), vegetable oil (Aureo), and polymer (BREAK-THRU) on the physical–chemical properties (surface tension, contact angle, volumetric mass, electrical conductivity, and pH), droplet size, and drift, using pure water as the control treatment (no adjuvant). Surface tension and contact angle were measured with a DSA30 droplet shape analyzer, while droplet size measurements were determined through a laser diffraction particle analyzer (Malvern Spraytec), using a single flat fan spray nozzle (AXI 110 03) operating at 0.3 MPa. Drift reduction potential was evaluated inside a wind tunnel with an air speed of 2 m s−1. All adjuvants reduced surface tension and contact angle compared to water. volumetric median diameter (VMD) increased for Aureo, Assist, and Agefix, generating coarse, medium, and medium droplets, respectively, while BREAK-THRU formed fine droplets, similar to those generated by water. Aureo had the greatest reduction in Relative Span Factor (RSF), with a reduction of 30.3%. Overall, Aureo, Assist, and Agefix adjuvants significantly reduced the percentage of droplets 500 µm. Drift reduction potential was achieved for all adjuvants, with Aureo showing the highest reduction of 59.35%. The study confirms that selecting the appropriate adjuvant can improve PPP application and promote environmental sustainability in agricultural practices.

Droplet size is a key factor in minimizing spray drift. Different types of adjuvants and sprayer operating pressures can affect the droplet size distribution in various ways. This study aimed to evaluate the effects of commercial adjuvants, namely, acids and surfactant (AS), silicone surfactant (SS), organosilicone surfactant (OS), mineral oil (MO and MO₂), and copolymer (CP) adjuvants, on the droplet spectra and physicochemical properties of aqueous solutions. Hydrogen potential (pH), volumetric mass ($VM$), electrical conductivity (EC), surface tension (ST), contact angle (CA), and droplet spectra were measured. The droplet spectrum variables, including volumetric diameters ($D_{v0.1}$, $D_{v0.5}$, and $D_{v0.9}$), the Relative Span Factor ($RSF$), and percentages of the total volume of droplets with a diameter smaller than 100 µm (V100) and larger than 500 µm (V500), were determined using a laser diffraction particle analyzer (Malvern Spraytec). Spraying tests were carried out using the AXI 11003 flat fan nozzle at pressures of (0.1, 0.2, 0.3, 0.4, and 0.5) MPa. The increase in pressure increased the V100 and the $RSF$, with greater sensitivity observed for SS. Adjuvants such as AS, MO₂ and OS showed a more balanced trend, with a smaller increase in fine droplets and a greater reduction in coarse droplets. The principal component analysis (PCA) revealed that the droplet spectrum variables were the ones that best explained the variation among the solutions. A negative correlation was identified between EC and other physicochemical properties, such as pH, ST, and CA. Therefore, these properties alone did not determine the atomization pattern. The study demonstrates that optimizing spray quality and minimizing drift require a combined consideration of adjuvant physicochemical properties and their interaction with operational pressure.

Spray drift of agricultural pesticides compromises application efficiency and increases environmental risk. This study evaluated the drift-reducing potential of three oil-based adjuvants through droplet spectrum characterisation and computational simulation. Experiments were conducted at the Agricultural Mechanisation Laboratory of the Federal University of Viçosa using a laser diffraction particle analyser (Malvern Spraytec) and an XR11003 nozzle positioned 0.3 m from the laser lenses, operated at 300 kPa. Droplet diameters corresponding to the 10th, 50th, and 90th percentiles of spray volume (Dv0.1, Dv0.5, and Dv0.9), droplet size uniformity (Span), and the volumetric percentage of droplets ?100 µm (%V?100 µm) were measured. These diameters, together with discharge height (0.5 m), wind velocity (2 m s?¹), temperature (25 °C), and relative humidity (75%), were used as inputs in the DRIFTSIM model. Water produced the lowest Dv0.5 (172.96 µm), the highest %V?100 µm (23.73%), and the greatest drift distance (9.88 m). The addition of adjuvants increased Dv0.5 and reduced %V?100 µm. Áureo provided the greatest reduction in drift distance (83.9%) and drift potential (71.5%), followed by Assist (71.96% and 58.9%) and Agefix (33.0% and 26.1%). Oil-based adjuvants significantly reduced drift, indicating their potential as effective tools to enhance spray efficiency, increase environmental safety, and minimise non-target contamination.